Some communities may resist invasion because they are dominated by ecosystem engineers. If these dominant species are removed by a catastrophic disturbance, they can be replaced by invasive species that will dramatically alter the ecosystem in a way that may prevent its recovery. Hurricanes represent a major source of such catastrophic disturbance to coastal communities. The removal of Florida rosemary, a native allelopathic shrub, by Hurricane Katrina may have promoted the spread of an invasive grass within interior dune communities on Horn and Petit Bois Islands, Mississippi. Interactions among these two ecosystem engineers and periodic hurricanes could contribute to the structure of scrub communities on Gulf Coast barrier islands.